In high capacity optical networks, an essential device is the N×N crossconnect switch. The function of this device is to provide at each node full connectivity among several incoming fibers, each carrying several wavelength channels. The switch must be nonblocking, and it must be fast and efficient [1-3]. These properties can be realized with minimal depth 2log N and low crosstalk by using a crossbar arrangement of binary trees, consisting of 2N(N−1)1×2 and 2×1 elements [1-3]. This approach, however, is difficult to realize in integrated form on a single wafer, because of its large number of waveguide crossings.
What is needed is an N×N crossconnect switch, which can be implemented without the use of waveguide crossings.